Justice S S Sateeshchandran issued the order on a petition by Mani seeking to modify bail conditions.
The court said after the two-month period starting today, Mani can enter Idukki without its permission.
Mani had created a political storm by stating that the CPI(M) had allegedly prepared a hit list in the 1980s to eliminate its opponents and had been arrested in connection with the 1982 murder of Anchery Baby. He was granted bail this January.
The investigation in the case was in the final stages and would be completed within two months, Director General of Prosecution submitted.